Copying welding equipment

ABSTRACT

In the tracking welder, left and right side wheels are supported rotatably by a pair of bearing units that are pivotally attached on a carriage, and this carriage is provided with a driving source for running the carriage, a transmission system for transmitting a rotational motion of the driving source to the left and right side wheels, a welding torch, a sensor for detecting a route to be welded, a track-controlling motor to be rotate in forward and backward directions in response to a detection signal of the sensor, and a steering system for turning the bearing units in an amount corresponding to a rotational amount of the track-controlling motor. According to this tracking welder, it is possible to automatically perform various kinds of welding including not only fillet welding of a corner between horizontally placed steel plate and web plate erected on the steel plate, but also butt welding of steel plates, for example.

Technical Field

[0001] This invention relates to a welding apparatus and moreparticularly to a tracking welder of which a carriage is so structuredas to travel along a predetermined welding line together with a weldingtorch mounted thereon.

Background Art

[0002] When fillet welding of a corner of metallic plates is carried outby running the carriage mounted with the welding torch, the travelingdirection of the carriage should be controlled so that the welding torchmay travel along the welding line.

[0003]FIG. 14 illustrates an example of the conventional trackingwelders. In a case of fillet welding of the corner made by a virtuallyhorizontally placed steel plate (a) and a steel web plate (b) erected onthe steel (a), a self-travelable carriage (d) mounted with a weldingtorch (c) is placed on the steel plate (a), and the welding of thecorner is automatically performed with the welding torch (c) at the sametime of running the carriage (d) along a tracking face, that is the webplate (b).

[0004] The carriage (d) is mounted with a front tracking roller (e)projecting toward the tracking face (the web plate) (b) and a reartracking roller (f) projecting at a long distance as compared with thefront tracking roller E, and by running the carriage (d) in direction(g) slightly inclined toward the tracking face (the web plate) (b), thefront tracking roller (e) and the rear tracking roller (1) become to bealways contact with the tacking face (the web plate) (b), and thus adistance between the welding torch (c) and the corner is kept constant.

[0005] However, as for the above-mentioned conventional tracking welder,while it is possible to automatically weld the corner between thehorizontally placed steel plate (a) and the web plate (b), there is aproblem in that such the machine is not available in a case the webplate (b) does not exist (in a case of butt welding, for example).

[0006] Moreover, even when welding the corner by utilizing the erectedwall b, there still remains a problem of limitation in the travelingdirections of the carriage (d), and it is impossible to perform weldingby running the carriage in the reverse direction from the arrow (g).

[0007] Furthermore, since the carriage (d) gradually approaches the webplate (b) while traveling, the wheels of the carriage (d) tend to bepushed back by the tracking rollers (e) and (f), and always slip in thelateral direction, thereby causing the strong frictional resistance andmaking the carriage (d) not to travel so smoothly. Further, since thetwo tracking rollers (e) and (f) press the web plate (b) while thecarriage (d) is traveling, there is another problem of a danger in thatthe web pate (b) pushed by the rollers (e) and (f) might come off fromthe steel plate (a) in a case where the web plate (b) is temporallytacked on the steel plate (a), and it becomes subject to solve theseproblems.

DISCLOSURE OF THE INVENTION

[0008] The present invention has been achieved in view of theaforementioned problems in the conventional arts, and it is an object toprovide a tracking welder, which is widely applicable in the welding ofvarious parts other than just a corner, which is able to perform weldingeven when the traveling direction of the carriage is reversed, andfurther, which can perform welding smoothly along the predeterminedroute without causing compulsive slipping to the wheels of the carriagewhile it is traveling.

[0009] The very investors found out that the above objects areattainable by setting a steering system to a carriage and controllingit, and thus comes to accomplish the present invention through theirdiligent scrutiny.

[0010] The tracking welder according to the present invention ischaracterized by supporting left and right side wheels by a pair ofbearing units attached pivotally on a carriage, and providing a drivingsource for running the carriage, a transmission system for transmittinga rotational motion of the driving source to the left and right sidewheels, a welding torch, a sensor for detecting a welding line, atrack-controlling motor to be rotate in forward and backward directionsin response to a detection signal of the sensor, and a steering systemfor turning the bearing units in an amount corresponding to a rotationalamount of the track-controlling motor on the carriage.

[0011] Further, in the first preferred embodiment of the tracking welderin the present invention, the transmission system is characterized bycomprising a hollow outer cylinder rotatably supported on the carrier tobe transmitted with the rotational motion of the driving source, anintermediate shaft disposed in the hollow of the outer cylinder andconnected with axles of the wheels through universal joints at both endsthereof, and a transmission pin passing through an oval hole formed inthe intermediate shaft and engaged to the outer cylinder at both endsthereof, as the second preferred embodiment of the tracking welder inthe present invention, the steering system is characterized bycomprising a pair of arm bolts protruding from outer faces of therespective bearing units, a connection bar pivotally connected with onepair of arm bolts at both ends thereof, and a lever secured on an outputshaft of the track-controlling motor and engaging with one of the armbolts at a free end thereof, and as the third preferred embodiment ofthe tracking welder in the present invention, it is characterized byfurther providing a suction system for attracting the carriage toward acarriage-running face so as to enable the carriage to travel on therunning face.

[0012] Furthermore, another tracking welder of the present invention isa welding apparatus for welding works made of non-magnetic metal witheach other, and is characterized by comprising a carriage traveling in astate of holding a welding torch, and a suction system for attractingthe carriage toward the works so as to enable the carriage to travel,and the suction system is provided with a flat base made of magneticmetal, and having a carriage-running face and a traveling route-settingmeans, a flexible suction cup formed with an aperture and fitted onreverse side of the carriage-running face of the base in a state ofdirecting the aperture toward the opposite direction of thecarriage-running face, a suction source for sucking air in the suctioncup, and a magnet disposed on the carriage for preventing the carriageto fall.

[0013] In the tracking welder of the present invention, the rotationalmotion of the driving source is transmitted to the wheels through thetransmission system, thereby running the carriage. When the sensormounted on the carriage detects displacement of the welding torch fromthe predetermined welding line, the tracking-controlling motor rotatesin response of the detection signal from the sensor, and the bearingunits turn in accordance with the rotational amount of thetrack-controlling motor through the steering system, whereby thedirection of the wheels is corrected according to the turn of thebearing units, and the carriage comes to travel along the predeterminedroute, in such manner the welding is completed without deviating fromthe predetermined welding line.

[0014] Further, in the tracking welder of the first preferred embodimentin the present invention, having the above described construction, theouter cylinder supported by the carriage rotates by the rotation of theprimary travel drive rotates, and the rotation of the outer cylinder istransmitted to the intermediate shaft by way of the transmission pin,whereby the rotation of the intermediate shaft is now transmitted to thewheels through the universal joints, and thus the carriage comes totravel smoothly.

[0015] Furthermore, in the tracking welder of the second preferredembodiment in the present invention, provided with the aforementionedconstruction, when the sensor detects the displacement amount of thewelding torch from the welding line while the carriage is traveling, thetrack-controlling motor rotates on basis of on the detection amount, thelever fixed on the output shaft of the track-controlling motor pressesone of the arm bolts, thereby transmitting this force to another armbolt through the connection bar, and in this way, both arm bolts come toturn in the same amount. Also, the bearing units coupled with the armbolt turn together with the wheels, and the direction of the wheels isautomatically corrected, whereby the carriage comes to travel along thepredetermined route.

[0016] As already mentioned, in the case where transmission system ofdriving force is provided with the a hollow outer cylinder rotatablysupported on the carrier to be transmitted with the rotational motion ofthe driving source, the intermediate shaft disposed in the hollow of theouter cylinder and connected with the axles of the wheels through theuniversal joints at both ends thereof, the direction of the wheels canbe changed without being impeded by the intermediate shaft because theuniversal joints are provided between the intermediate shaft andrespective wheels, and the intermediate shaft is disposed so as to bepossible to swing around the transmission pin serving as a fulcrum.

[0017] Further, in the tracking welder of the third preferred embodimentin the present invention, which is further provided with the suctionsystem for attracting the carriage toward the carriage-running face soas to enable the carriage to travel on the running face, it is possibleto hold the carriage on the carriage-running face, thereby enabling thewelder to perform butt welding of works made of non-magnetic metal andmulti-layer welding at a corner of works, for example, and applicationfields of this tracking welder come to be increased.

[0018] Furthermore, in the second tracking welder of this invention,which is most suitable for butt welding of non-magnetic metal works, thebase is adsorbed on the works by sucking air in the suction cup usingthe suction source of the suction system, thereby completing setting forthe works, on the other hand, the adsorption state of the base on theworks is released by stopping the operation of the suction source of thesuction system and introducing air into the suction cup, whereby thebase becomes removable. In this manner, arrangements and withdrawals asa whole become easier and possible to be completed in a short time. In apreferred embodiment of the second tracking welder in the presentinvention, the setting of the route for the carriage becomes availablesimple.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a bottom view illustrating an embodiment of the trackingwelder according to this invention;

[0020]FIG. 2 is an explanatory view from the direction of arrow A inFIG. 1;

[0021]FIG. 3 is an explanatory view from the direction of arrow B inFIG. 1;

[0022]FIG. 4 is an explanatory view from the direction of arrow C inFIG. 1;

[0023]FIG. 5 is a sectional view along section lines D-D of FIG. 4;

[0024]FIG. 6 is a sectional view along section lines E-E of FIG. 5;

[0025] FIG. 7 is an explanatory view illustrating the action of thesteering system,

[0026]FIG. 8 is an explanatory view illustrating a state of butt weldingusing the tracking welder according to the embodiment of this invention;

[0027]FIG. 9 is a perspective view illustrating another embodiment ofthe tracking welder according to this invention;

[0028]FIG. 10 is a side view of the tracking welder shown in FIG. 9;

[0029]FIG. 11 is a front view of the tracking welder shown in FIG. 9;

[0030]FIG. 12 is a perspective view illustrating the other embodimentsof the tracking welder according to this invention;

[0031]FIG. 13 is a side view illustrating other embodiment of thetracking welder according to this invention; and

[0032]FIG. 14 is a top view illustrating the action of the conventionaltracking welder.

BEST MODE FOR CARRYING OUT THE INVENTION

[0033] The present invention will be described in detail on basis ofembodiments thereinafter, however this invention is not limited to theseembodiments.

EXAMPLE 1

[0034] An embodiment of the tracking welder according to this inventionis shown in FIG. 1 to FIG. 8.

[0035] A carriage 1 is composed of a rectangular base plate 1 a andrectangular frame 1 b disposed in the center on the bottom face of thebase plate 1 a as shown in FIG. 1 and FIG. 4, and a pair of wheels 2,which functions as front wheels on left and right side, is supported bybearing units 3, respectively.

[0036] The bearing unit 3 is provided with sidewalls 3 b extendingdownward from the respective ends of an upper plate 3 a, and a back wall3 c extending downward from the back end of the upper plate 3 a. Athrust pin 4 protruding from the upper face of the upper plate 3 a isinserted into a bearing 5, which is fitted into a through hole formed inthe carriage 1, and the end of the thrust pin 4 projecting out from thethrough hole is locked by a stopper ring 6.

[0037] As shown in FIG. 5, bearings 7 are fitted into holes formedthrough the both sidewalls 3 b of the bearing unit 3, and an axle 2 a ofthe wheel 2 is supported by these bearings 7. Accordingly, the wheels 2are structured to rotate around the axles 2 a, and so designed as to beable to change the running direction around the thrust pins 4.

[0038] The bearing unit 3 is provided with an arm bolt 8 on the backwall 3 c thereof. Further, a motor 9 is mounted on the upper face of thecarriage 1 as a driving source, as shown in FIG. 4, and attached with asprocket 10 on an output shaft thereof.

[0039] As also shown in FIG. 8, carriage 1 is mounted with a weldingtorch T and a sensor 30 for detecting displacement by applying a laserbeam to the welding line L, and a track-controlling motor 11 is attachedon the outer wall of the frame 1 b, which rotates by receiving adetection signal from the sensor 30 as shown in FIG. 2. The motor 11fixed with a lever 12 on the output shaft thereof.

[0040] An optical axis LB of the sensor 30 is focused to the weldingline L through a turning operation of a knob 31, and the welding torch Tis so structured as to weave within a range shown by arrows around anaxis P.

[0041] As also shown in FIG. 3, the free end of the lever 12 is engagedwith the arm bolts 8 protruding from one of the bearing units 3, and thetwo arm bolts 8 are pivotally connected to respective ends of aconnection bar 14 through forked fittings 13 secured on the free ends ofthe arm bolts 8.

[0042] Namely, the track-controlling motor 11 works on basis of thesignal from the sensor 30, thereby swinging the lever 12 in the normalor the reverse directions, and the swing of the lever 12 is transmittedto the bearing units 3 of the left and right sides through the arm bolts8, thereby changing the direction of the left and right side wheels 2together with the bearing units 3 toward the left or right side from thetraveling direction of the carriage 1. In this manner, the steeringsystem is composed.

[0043] As also shown in FIG. 6, a pair (left and right) of cylinderbrackets 15 are fixed on the bottom face of the base plate 1 a of thecarriage 1 with bolts 16, a hollow outer cylinder 18 is rotatablysupported by bearings 17 fitted into through holes of the cylinderbrackets 15, and a sprocket 19 disposed at one end of the outer cylinder18 is connected with a sprocket 10 disposed to the output shaft of themotor 9 through a chain 20.

[0044] A chain 25 is stretched between a sprocket 21 disposed at anotherend of the outer cylinder 18 and a sprocket 24 disposed to an axle 23 ofrear wheels 22. As shown in FIG. 5, the intermediate shaft 26 disposedin the hollow of the outer cylinder 18 is connected to the axles 2 a ofthe front wheels 2 through universal joints 27 at the respective endsthereof, and a transmission pin 29 is passed through an oval hole 28formed in the middle of the intermediate shaft 26 and engaged to thehollow outer cylinder 18 at the both ends thereof.

[0045] That is to say, when the motor 9 starts, the rotational motion ofthe motor 9 is transmitted to the outer cylinder 18 through the sprocket10, the chain 20, and the sprocket 19, the rotational motion of theouter cylinder 18 is transmitted to the intermediate shaft 26 throughthe transmission pin 29, whereby the front wheels 2 come to rotate andat the same time, the rear wheels 22 also come to rotate by the powertransmitted to the rear axle 23 through the sprocket 21, the chain 25,and the sprocket 24, and in this way, the transmission system fordriving force is composed.

[0046] In this time, the universal joint 27 is disposed between the axle2 a of the wheel 2 and the intermediate shaft 26 transmitting the power,and the universal joint 27 is fitted to the intermediate shaft 26 with aplay, therefore the power of the intermediate shaft 26 is transmitted tothe wheels 2 smoothly even when correcting the direction of the wheels 2while traveling.

[0047] Furthermore, this tracking welder is provided with a suctionsystem 40 for attracting the carriage 1 on a carriage-running face F soas to enable the carriage 1 to travel, as shown in FIG. 4.

[0048] The suction system 40 is provided with a suction sleeve 41disposed to the carriage 1 to communicate with the inside of the flame 1b, packing 43 made of silicon rubber or so, attached on the lower end ofthe frame 1 b through a bottom plate 42 and set in near contact with thecarriage-running face F, and a vacuum pump (not shown) working as asuction source and connected with the suction sleeve 41 through a hose.The suction system 40 is designed to attract the carriage 1 so that thecarriage 1 may travel on the carriage-running face F by actuating thevacuum pump and sucking air in the frame 1 b of the carriage 1.

[0049] Next, tan explanation will be given as to an operation forperforming welding along the predetermined welding line by using theaforementioned the tracking welder.

[0050] As shown in FIG. 8, in a case of carrying out butt welding ofsteel plates, at first, the tracking welder is placed on the runningface F of the steel plates in a state of directing the front wkeels 2toward the welding direction (on the left side in FIG. 8). Then, theoptical axis LB of the sensor 30 is adjusted with the welding line L bythe turning operation of the knob 31, and the welding torch T isapproached to the starting point of the welding.

[0051] Following suction of air in the inner part of the frame 1 b ofthe carriage 1 to enable the carriage 1 to travel in a state of beingattracted on the carriage-running face F by actuating the vacuum pump, aswitch on a cover (not shown) provided on the carriage 1 is operated onto supply power to the motor 9. In this manner, the carriage 1 of thetracking welder comes to travel over the welding of the predeterminedwelding line L by rotating the wheels 2 at the same time of making thewelding torch T to weave in the range of arrows around the axis P.

[0052] Then, when the sensor 30 on the carriage 1 detects deviation(displacement) of the present traveling route of the carriage 1 from thepredetermined welding line L, the track-controlling motor 11 rotates asmuch as an amount corresponding to the displacement amount in responseto the detection signal from the sensor 30, the lever 12 fixed to thetrack-controlling motor 11 presses the arm bolt 8 by the rotation of themotor 11, whereby the direction of the wheels 2 is correct according tothe turn of the bearing units 3 pushed by the arm bolts 8, and thuscarriage 1 of the tracking welder comes to travel always withoutdeviating from the predetermined welding line L.

[0053] Under this operation, as illustrated in FIG. 7, since theuniversal joint 27 is disposed between the axle 2 a of the wheel 2 andthe intermediate shaft 26 transmitting the power, and the universaljoint 27 is fitted with the intermediate shaft 26 with the play, theintermediate shaft 26 just inclines slightly when the direction of thewheels 2 is corrected during the travel, so that it is possible tosmoothly transmit the power to the wheels 2.

[0054] In addition to above, the tracking welder having theaforementioned construction may be also mounted with an equalizersystem.

EXAMPLE 2

[0055] Another embodiment of the tracking welder according to thepresent invention is shown in FIG. 9 to FIG. 11.

[0056] The tracking welder shown in FIG. 9 is a welding apparatus forusing butt welding of works W made of non-magnetic metal, such asaluminum and stainless steel. A suction system 60 in this trackingwelder, which attracts a carriage 51 mounted with a welding torch 54toward the works W so as to enable the carriage 51 to travel, is mainlycomposed of a flat base 62 made of magnetic metal and provided with acarriage-running face 62 a and a tracking wall 62 b as a travelingroute-setting means, a flexible suction cup 61 fitted on the reverseside (lower side in the figures) of the carriage-running face 62 a ofthe base 62 in a state of directing an aperture 61 a toward the oppositedirection of the carriage-running face 62 a, a suction pump (suctionsource) 63 connected with a suction port 61 b of suction cup 61 througha hose 64 to such the air in the suction cup 61, and a magnet (notshown) disposed on the carriage 51 for preventing the carriage 51 fromfalling as shown in FIG. 10 and FIG. 11.

[0057] The suction system 60 is so designed as to enable the base 62 tobe attached not only on the upper face of the works W, but also on theside face and the bottom face of the works W by actuating the suctionpump 63 and sucking air in the suction cup 61, and the other hand, as toenable the base 62 to be easily detached from the works W by stoppingthe operation of the suction pump 63 and opening the inside of thesuction cup 61 into the atmosphere.

[0058] In this case, the carriage 51 is installed with a pair of thetracking arms 51 a on the side face thereof, and so structured as totravel along the predetermined running route by setting the carriage 51to slide-contact the tracking arms 51 a with the tracking wall 62 b ofthe base 62 in a state of attaching the base 62 to the works W so thatthe tracking wall 2 b positioned at the side edge of the base 62 may besituated along the butt welding line L of the works W.

[0059] In this tracking welder, the flat base 62 made of magnetic metaland possible to set the traveling route of the carriage 51 is adsorbedon the works W, and the setting of the base 62 against the works W iscompleted by actuating the suction pump 63 of the suction system 60 andsucking air in the suction cup 61 after placing the base 62 on the worksW so as to situate the tracking wall 62 b along the butt welding line Lof the works W. On the other hand, the adsorption state of the base 62on the works W is cancelled and the withdrawal of the base 62 becomespossible by stopping the operation of the suction pump 63 of the suctionsystem 60, and the respective operation in arrangements and withdrawalsis completed easily in a short time, accordingly workability of the buttwelding comes to be improved remarkably.

[0060] Further in this welder, the traveling route of the carriage 51 ismade by the tracking wall 62 b of the base 62, therefore the setting ofthe traveling route of the carriage 51 is done with the simpleconstruction.

EXAMPLE 3

[0061] The other embodiment of the tracking welder according to thepresent invention is shown in FIG. 12. There are differences betweenthis welder and the welder according to the preceding embodiment(Example 2) in the point that the base 62 is formed with rails 62 c as atraveling route-setting means so as to run a carriage 51A along thepredetermined traveling route by these rails 62 c as shown in FIG. 12,and the tracking welder according to this embodiment is the same as thewelder according to the preceding embodiment excepting the constructionas mentioned above.

[0062] Therefore, also in this welder, the respective operation inarrangements and withdrawals is completed easily in a short time,accordingly workability of the butt welding comes to be improvedremarkably, additionally the setting of the traveling route of thecarriage 51A is done with the further simple construction since thetraveling route of the carriage 51 can be set by the rails 62 c formedon the base 62.

EXAMPLE 4

[0063]FIG. 13 illustrates the other embodiment of the tracking welderaccording to the present invention. There are differences between thiswelder and the welders according to the preceding embodiments (Example 2and 3) in the point that the suction port 61 b of the suction cup 61 inthe suction system 60 is disposed on the carriage-running face 62 a ofthe base 62 in a position where the carriage 51 may travel withouthindrance and the suction port 61 b and the suction pump 63 areconnected through the hose as shown in FIG. 13, and the tracking welderaccording to this embodiment is the same as the welders according to thepreceding embodiments excepting the construction as mentioned above.

[0064] Also in this welder, the respective operation in arrangements andwithdrawals is completed easily in a short time.

[0065] In the aforementioned examples shown in FIG. 9 to FIG. 12, thecases are illustrated where the tracking welder according to thisinvention is set on the upper surface of the work W, however the presentinvention is not limited merely to such the examples and it is also setthe welder on the side face as shown in FIG. 13 (Example 4), or on thebottom face of the work W.

INDUSTRIAL APPLICABILITY

[0066] As described above, in the tracking welder according to thepresent invention, providing the aforementioned construction, anexcellent effect can be obtained in that it is possible to carry outvarious kinds of automatic welding, including butt welding of steelplates with each other, without being limited only in fillet weldingbetween the steel plate and the web plate erected on this steel plateunlike the conventional tracking welder.

[0067] Also, in a preferred embodiment of the tracking welder accordingto the present invention, providing the aforementioned construction, thetraveling direction is not limited in just one direction, but it ispossible to apply welding from the reverse direction. In anotherpreferred embodiment of the tracking welder according to the presentinvention, having the aforementioned construction, it is possible tosmoothly perform welding along the predetermined route without causingunnatural slipping to the wheels while the carriage is traveling.

[0068] Furthermore, in the other preferred embodiment of the trackingwelder according to the present invention, providing the aforementionedconstruction, it comes further to perform, for example, butt welding ofthe works made of non-magnetic metal, and it becomes possible to realizeenlargement of applicable fields of this tracking welder.

[0069] Moreover, in the other preferred embodiment of the trackingwelder according to the present invention, it is possible to carry outthe respective operation in arrangements and withdrawals simply in ashort time in butt welding of the works made of non-magnetic metal, andconsequently, possible to realize remarkable improvement of theworkability of the butt welding. Further in the other preferredembodiment of the tracking welder according to the present invention, itis possible to set the running route of the welding carriage withoutcomplicating the construction, in addition to the same effects obtainedin the aforementioned tracking welders.

What is claimed is:
 1. A tracking welder for automatically welding worksalong a predetermined welding line, comprising: a carriage provided withleft and right side wheels rotatably supported respectively through apair of bearing units pivotally mounted thereon; a driving sourcemounted on the carriage for driving said carriage; a transmission systemmounted on the carriage for transmitting a rotational motion of saiddriving source to said left and right side wheels; a welding torchmounted on the carriage; a sensor mounted on the carriage for detectingthe welding line; a tack-controlling motor mounted on the carriage androtating in forward and backward directions in response to a detectionsignal from said sensor; and a steering system mounted on the carriagefor turning said bearing units as much as an amount corresponding to arotational amount of said track-controlling motor.
 2. A tracking welderas set forth in claim 1, wherein said transmission system is providedwith: a hollow outer cylinder rotatably supported on said carriage to betransmitted with the rotational motion of the driving source; anintermediate shaft disposed in the hollow of said outer cylinder andconnected with axles of said wheels through universal joints at bothends thereof, and a transmission pin passing through an oval hole formedin said intermediate shaft and engaged to said outer cylinder at bothends thereof.
 3. A tracking welder as set forth in claim 1 or 2, whereinsaid steering system is provided with: a pair of arm bolts protrudingfrom outer faces of said respective bearing units; a connection barpivotally connected with said one pair of arm bolts at both endsthereof, and a lever secured on an output shaft of saidtrack-controlling motor and engaging with one of said arm bolts at afree end thereof.
 4. A tracking welder as set forth in any one of claims1 to 3, wherein said welder is further provided with a suction systemfor attracting the carriage toward a carriage-running face so as toenable the carriage to travel on the running face.
 5. A tracking welderfor automatically welding works made of non-magnetic metal along apredetermined welding line, comprising: a carriage traveling in a stateof holding a welding torch; and a suction system for attracting saidcarriage toward the works so as to enable the carriage to travel,wherein said suction system is provided with a flat base made ofmagnetic metal, and having a carriage-running face and a travelingroute-setting means; a flexible suction cup formed with an aperture andfitted on reverse side of the carriage-running face of said base in astate of directing the aperture toward the opposite direction of thecarriage-running face; a suction source for sucking air in said suctioncup; and a magnet disposed on the carriage for preventing the carriageto fall.
 6. A tracking welder as set forth in claim 5, wherein said baseis provided with a tracking wall or a rail thereonto as said travelingroute-setting means.